Estudo comparativo de duas técnicas de lavra em barragem de rejeito sob o ponto de vista geotécnico

Abstract

Iron ore mines located in Iron Quadrangle has been recovering poor grade ore since 1970, by the shortage of high grade ore, as hematite. The mines next challenge is how to re-treats iron ore from tailings deposits (tailings dams) and waste rock piles. Feasibilities studies were carried by scientific institutions and mines in the state of Minas Gerais, Brazil. So, metallurgical plants were modernized to enable tailings recovery. Tailings reclaiming can be done with dry and wet methods. Mechanical reclamation and hydraulic mining were the considered methods for this study. Mechanical reclamation involves earth-moving equipments such as bulldozers, frontend loaders and trucks. Hydraulic mining involves jets of high pressure monitors guns at the tailings and the slurry is pumped to the treatment complex. The focus of this study was evaluating the geotechnical impact of these two reclamation methods on a tailings storage facility. The tailing storage facility is a drained stacking of granular tailings, constructed by hydraulic slurry placement, closed for 15 years. Thus, stress-strain, seepage and stability analysis were carried out, including the assessment of the potential for flow failure. Results showed that the mechanical reclamation does not affect the stability of the Drained Stacking. Hydraulic mining, also, does not affect the stability of the Drained Stacking. Despite, if the internal drainage system fails, hydraulic mining may induce failures.